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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *   http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.apache.myfaces.shared_orchestra.util;
20  
21  import java.lang.reflect.Method;
22  import java.util.ArrayList;
23  import java.util.List;
24  
25  /**
26   * Various helpers to deal with exception
27   * 
28   * @author imario@apache.org
29   */
30  public final class ExceptionUtils
31  {
32      private ExceptionUtils()
33      {
34      }
35  
36      /**
37       * <p>
38       * returns a list of all throwables (including the one you passed in) wrapped by the given throwable.
39       * In contrast to a simple call to <code>getClause()</code> on each throwable it will also check if the throwable class
40       * contain a method <code>getRootCause()</code> (e.g. ServletException or JspException) and call it instead.
41       * </p>
42       * <p>
43       * The first list element will your passed in exception, the last list element is the cause. 
44       * </p>
45       */
46      public static List getExceptions(Throwable cause)
47      {
48          List exceptions = new ArrayList(10);
49          exceptions.add(cause);
50          
51          do
52          {
53              Throwable nextCause;
54              try
55              {
56                  Method rootCause = cause.getClass().getMethod("getRootCause", new Class[]{});
57                  nextCause = (Throwable) rootCause.invoke(cause, new Object[]{});
58              }
59              catch(Exception e)
60              {
61                  nextCause = cause.getCause();
62              }
63              if (cause == nextCause)
64              {
65                  break;
66              }
67              
68              if (nextCause != null)
69              {
70                  exceptions.add(nextCause);
71              }
72              
73              cause = nextCause;
74          }
75          while (cause != null);
76          
77          return exceptions;
78      }
79  
80      /**
81       * Find a throwable message starting with the last element.<br />
82       * Returns the first throwable message where <code>throwable.getMessage() != null</code> 
83       */
84      public static String getExceptionMessage(List throwables)
85      {
86          if (throwables == null)
87          {
88              return null;
89          }
90  
91          for (int i = throwables.size()-1; i>0; i--)
92          {
93              Throwable t = (Throwable) throwables.get(i);
94              if (t.getMessage() != null)
95              {
96                  return t.getMessage();
97              }
98          }
99          
100         return null;
101     }
102 }